This grant request proposes an integrated multilevel approach to define the role of the cytochrome P450 4F (CYP 4F) subfamily and CYP 2D18 in modulation of the inflammatory cascade following traumatic brain injury (TBI) using a controlled cortical impact model system. In humans, closed head injury resulting from various sources of trauma to the brain (e.g., traffic accidents, violence) constitutes a serious, often intractable clinical problem frequently leading to death or the situation where discontinuation of artificial life support becomes a question. TBI triggers the inflammatory cascade prompted through leukotriene B, and prostaglandins causing the influx of fluids, ions and cells into brain tissue - the subsequent brain swelling often leading to coma. Our approach to this problem is prompted first by the demonstration that the CYP 4F subfamily enzymes can metabolize the leukotriene and prostaglandin mediators of inflammation to inactive products with the possible effect of moderating the inflammatory cascade. Second, it is prompted by preliminary data which show that three out of four of the rat CYP 4F forms studied show a decrease in expression in the hippocampus at 24 hours after trauma and an increase in expression at three days through three weeks after cortical impact (i.e., the recovery or reversal of inflammation phase). We will pursue these preliminary data by defining the changes in expression of CYP 4F forms and CYP 2D18 in various brain regions and distal tissues (i.e., liver, kidney, etc.) as a function of time after impact. We will express, purify and characterize the catalytic activities toward leukotriene and prostaglandin of CYP 4F1 and CYP 4F6 the two remaining forms we have not characterized. We will correlate changes in CYP4F and 2D18 expression following TBI with cellular markers of inflammation and changes in levels of humoral signaling molecules (e.g. IL-6, IL-lbeta, TNFalpha) to test the hypothesis that CYP4Fs modulate inflammatory response as proposed. We will also define changes in the expression of CYP4F and 2D18 and changes in markers of inflammation and signaling molecules in the mouse model of TBI developed by Dr. P. Dash the co-investigator in order for normal and CTP4F14 null phenotype mice after TBI to define the role of a specific CYP4Fs. We feel these approaches will allow a better definition of the modulation of the inflammatory cascade after TBI.